Computer systems are provided for modeling complex structures and for analyzing their performance under a predetermined set of load cases. Such systems are arranged to enable the structure to be designed so that it performs as required during its operation or deployment. Elements of the structure are generally modeled and analyzed under the assumption that their behavior is purely in-plane. For example, given a stiffened panel comprising a panel element and one or more stiffener elements, the analysis would model the panel as carrying only membrane fluxes, that is, biaxial traction-compression and shear loads, while the stiffener elements generally carry only traction-compression forces.
However, some real-world factors are not accounted for in such methods of structural modeling. This could cause a problem if such real-world factors have a critical effect on the performance of the structure. For example, the real structure could fail at lower loads than the modeled structure. Furthermore, the failure may be unpredictable. One solution that is provided to account for such real-world factors, is to build additional tolerance into the structure to enable it to cope with the assumed real-world factors.